[clang] [ExprConstant] Handle shift overflow the same way as other kinds of overflow (PR #99579)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman commented:

Thank you for working on this! In general, this is heading in the right direction. Though I do agree with @shafik that it would be nice to add additional test coverage for the changes which didn't modify existing test behavior. Also, we should have a release note for the changes and probably a mention about it being a potentially breaking change because we're rejecting code we used to explicitly accept as an extension.

https://github.com/llvm/llvm-project/pull/99579